Stretched pulse fiber lasers have been taught in the prior art. See for instance, U.S. Pat. No. 5,513,194 issued Apr. 30, 1996 to Tamura et al. (“Stretched-pulse Fiber Laser”), which is incorporated herein by reference in its entirety.
Stretched pulse fiber lasers have been shown capable of producing high energy, ultra short laser pulses. The laser cavity of a conventional stretched pulse fiber laser is formed with a negative group dispersion velocity fiber segment joined in series with a positive group dispersion velocity fiber segment. The positive group dispersion velocity fiber is typically doped with a rare earth element such as erbium or thulium and is utilized as the means of providing laser radiation gain in the laser cavity.
The physical properties of a rare earth doped fiber constrain laser radiation gain to occur in a narrow band of wavelengths. Erbium fiber based lasers, for example, are only capable of providing laser radiation gain in the 1550 nm band. Collectively, stretched pulse fiber lasers based on rare earth doped fibers have been unable to satisfy the need to produce high energy, ultra short pulses in a variety of different wavelength bands.